The normal mechanism of viral entry requires interactions between viral envelope proteins and cellular receptors and, in some cases, also cellular co-receptors. Such a mechanism presents limitations in the ability to target viral vectors to specific cell types. For example, such a mechanism makes it difficult to target viral vectors of interest to cell types lacking cellular receptors which interact with viral envelope proteins of the viral vectors of interest.
Thus, there is a continued need to develop new and improved methods for targeting viral vectors to specific cell types.